Method of preparing an



Patented Jan. 2, 195] r 'IEI) STATES P N ICE METHOD OF PREPARING AN ISOCYANURATE Donald W. Kaiser, Old Greenwich, and Dagfrid Holm-Hansen Church, Stamford, Conn., as-

- signors to American Cyanamid'Company, New

York, N. Y., a corporation of Maine No Drawing. Application July 26, 1949,

Serial No. 106,976

ticularly it is concerned with the method of preparing an isocyanurate which comprises effectf ing reaction under heat between (1) an alkali metal; cyanate, more particularly a cyanate of sodium, potassium, lithium, rubidium or caesium, and (2) a hydrocarbon halide (active hydrocarbon halide) represented by the formula RX,

described in the first paragraph of this specifi- 12 Claims. (Cl. 260-248) 2 cation and more fully hereafter. More particu larly we have found that such isocyanurates can be prepared by heating under atmosphericf pressure or, preferably, under superatmospheric pressure, e. g., at pressures ranging from 20 pounds to 10,000 pounds or more per square, f inch, and at a temperature within the range of about 65 0. (preferably at least about 100 C;) f to about 175 C., or a little higher, e. g., about,"

where X represents halogen (e. g., chlorine, 200 6., a mi u consisting essentially of an bromine, iodine) and R represents a radical se alkali-metal Cyanate and a hydrocarbon halide lected from the class consisting of alkyl (inlepmsented by h formula RX, Where ndii'. eluding cycloalkyl), alkenyl (including cyclo- X a the meanings s given h i b ,j alkenyl), aralkyl and araikenyl radicals. Thus, 15 fore, a d as. h h rd essentlal po nt, t hydrocarbon halide can be one which is acetonltrlle or other inert, non-hydroxylated embraced by the formula RX, but which can I solubilizing agent for increasing the solubility of be represented, for example, by the more specific the alkali-119F211 cyanate m the wt -I i} form l RC1, Where R has the same meaning Such an addltive also can be described more as given above with reference to- RX. In all gflinemjlly a reactlfm medlum that a cases the reaction is effected while the reactants F m Whlch reactlon 133139619 9,, of 1) and (2) are incorporated in a suitable alk'fubmetal Pyanate and W hydrocarbon-f3 'a medium, more particularly while they halide. Reactlon at atmospherlc pressure, e. g. are admixed with an inert, non-hydroxylated byqljleatmg Such pressure. under the solubilizing agent for improving the solubility 5 boning temperftture of the reactflon m n, of the alkali-metal cyanate in the reaction mass,) emfny less satlsfatctory from practlcal 7 i: specifically acetronitrile. The isocyanurate pomt The reactlon i prefeliably agltatedi which is thereby produced is then isolated from F- y mechanical Surfing dmimg the Team? the resulting reaction a tlon period, which may range, for instance, from The isocyanurates resulting from the method 535 g g: 1 23 3 2 i gg ii zf gfig xr of our invention may be represented by the general formula perature of reaction, the particular reactant and molar proportlons thereof which are em I 1 ploye'd, kind of apparatus used, and other .in-fff. fluencing' factors. l i

3 Taking potassium cyanate as illustrative 'of the alkali-metal cyanate employed, the above I} 0: =0 reaction may be illustrated by the following equa- 1,

4 tion: 7 i n o i i 40 inert (3 1 where R. has the same meaning as given above solubmzing with reference to the formula RX for the hy- 3KOCN 3RX f}: T drocarbon halide of (2).

It was known prior to our invention that isocyanurates of the kind embraced by Formula I could be prepared by rearrangement of a normal cyanurate by heating; and also by reaction It was quite fi lg and unexpected to of a silver salt of cyanuric acid with an alkylatfind hatan alkali-metal cyanate and an active ing' agent such ifor example as iodide hydrocarbon 0f the described under The present invention is based on our discovery of the first'pamgraph herein could be caused that isocyanurates of the kind embraced by to react together 3 isocyamlpmtei Formula I can be produced in yields asv high'as Ordinarily it m expected that if a t: e 80% from-relatively inexpensive, non-toxic maaction occurred It mi takFthe purse terials by a direct, one-step process as briefly trated by the fOIIQWmg equa ion? 3 or, the course illustrated by the following equation:

The chosen hydrocarbon halide is dependent upon the particular isocyanurate which it is desired to produce. Illustrative examples of hydrocarbon halides that can be used are benzyl, phenylethyl and other aralkyl chlorides, bromides and iodides; methyl, ethyl, propyl, is- :2

ence of which the reaction can be effected,

although with less satisfactory results than with acetonitrile, are propionitrile, ,B-methoxypropionitrile, dimethylcyanamide, acetone, dioxane and nitrobe'nzene. The water-soluble, non-hydroxylated solubilizing agents are preferred over those which are water-insoluble or have a low order of solubilit in water.

The molar ratios of alkali-metal cyanate and hydrocarbon halide can be varied fairly widely, since the excess over stoichiometrical proportions is merely present in the reaction mass as unreacted or partly reacted material. For example, both of the reactants can be used in equal molar proportions, or with the alkali-metal cyanate or the hydrocarbon halide in excess of the other, e. g., from 0.5 to or mole per cent, or even as much as mole per cent, of the one in excess of the other. The acetonitrile or other solubilizing agent for the alkali-metal cyanate can be varied as desired or as conditions may require, e. g., a volume amount ranging from about to about 20 times the total volume of the alkalimetal cyanate and hydrocarbon halide at the reaction temperature.

If desired, thereaction can be accelerated by incorporating a suitable catalyst into the reaction mass, for instance a tertiary-amine, e. g., triethyl, tripropyl, triisopropyl, tributyl, triamyl or other trialkyl amine, pyridine, etc.; or, when a hydrocarbon chloride, e. g., an alkyl chloride, is employed as a reactant, the catalyst can be an alkalimetal iodide such as sodium iodide, potassium iodide, etc. If a catalyst is used the amount thereof can be varied as desired or as conditions may require, but ordinarily the catalyst is employed in an amount corresponding to from about 0.1% to about 10% by weight of the amount of A mixture of the above ingredients was heated and agitated in a rocking-type autoclave for 3 hours at 150 C. under superatmospheric pressure. After filtering off the resulting salt (KCl) and distilling the low-boiling fraction at atmospheric pressure, the residue distilled between 107 C. and 114 C. under a pressure of 0.5 mm. There was obtained 69 parts of triallyl isocyanurate containing some solid material which slowly crystallized on standing. Upon filtration of the crude product, 2.5 parts of crystals of sym.-diallylurea was obtained. Th yield of triallyl isocyanurate was A sample of the crude triallyl isocyanurate from which the diallylurea had been filtered ofi gave the following results when analyzed for nitrogen;

%N Calculated for C12H15N3O3 16.86 Found 16.78

Crystallization of the sym.-diallylurea from cyclohexane gave crystalline plates melting at C. A mixed melting point of these crystals with a known sample of sym.-diallylurea showed no depression.

The formation of sym.-diallylurea as on of the reaction products inthe above example, and in other examples which follow, is the result of the presence of a slight quantity of water in the initial reactants when they are charged to the clave.

Example 2 Same as in Example 1 with the exception that 76.5 parts of allyl chloride was used. In other words the potassium cyanate and allyl chloride were employed in equal molar proportions. There was obtained 63 parts of crude triallyl isocyanurate boiling within the range of 103113 C. at 0.3 mm. pressure. The crude triallyl isocyanurate contained a small amount of sym-di'allylurea.

Example 3' Same as in Example 2 with the exception that The yield of crude triallyl isocyanurate was 59.5 parts. which boiled at 1.05-112 C. under a pressure of 0.5 mm. and from which 5 parts of symwdiallylurea was removed by filtration.

Example 4 Approx Parts Molar Ratios Potassium cyanate (94.2%) 215. 0 2. 5 Ally] chloride 198.9 2. 6 Acetonitrile 978. 5

The above ingredients were heated together with stirring for 3 hours at C. under superatmospheric pressure. Th yield-of triallyl isocyanurate was 51.5 parts, while the yield of symdiallylurea was 23.5 parts. There remained in the reaction vessel '70 parts of black, resinous material.

Example 1 Example 5 A prox. Approx Parts lelolar 70 Parts Molar Ratios Ratios Potassium cyanate (94.2%) .1 86. 0 1'. 0 Potassium cyanate (94.2%) 85, 0 1,.0 Ally] chloride 80.5 1.05 Allyl chl0ride 80.5 1.05 Acetonitrile -4 391.4 Nitrob 993.4

A mixture of the above ingredients was heated and agitated in a rocking-type autoclave for.3 hours at 150 C. under superatmospheric pressure, yielding 6 parts of triallyl isocyanurate and 15 parts of residue.

Example 6 Approx. Parts Molar Ratios Potassium cyanate (94.2%) 24. l l. Allyl chloride 22. 4 l 04 fl-Methoxypropionitrile 131. 0

were heated together with agitation in a rockingtype autoclave for 3 hours at 150 C. under superatmospheric pressure, yielding 2.5 parts of triallyl isocyanurate which boiled at 105-112 C. under a pressure of 0.1 mm. The residue amounted to 10 parts.

Example 7 Approx. Parts Molar Ratios Potassium cyanate {02.67 87. 1.0 Allyl chloride 80. 5 1.05 Propionitrile 391. 5

triallyl isocyanurate, which corresponds to about 34% of the theoretical yield.

Example 8 Approx. Parts Molar Ratios Potassium cyanate (92.6%) 87. 5 1. O Ally] chloride 80. 5 1.05 Dimethylcyanamide 443. l

A mixture of the above ingredients was heated with agitation in a rocking-type autoclave under superatmospheric pressure for 3 hours at 150 C. The resulting reaction mass was filtered to remove the inorganic solid (KCl plus unreacted KOCN). The dimethyl cyanamide was distilled from the filtrate under a pressure of 30 mm, while the residue was distilled at 0.05 mm. pressure. A solid co-distilled with the triallyl isocyanurate. Sella-- ration of the two products gave 14 partsof triallyl isocyanurate (17% of the theoretical) and parts of N,N-dimethylurea, which latter is formed as a result of hydrolysis of the dimethylcyanamide. The formation of N,N-dimethylurea can be avoided by thoroughly drying all of the Distillastarting materials and by carefully excluding water or moisture from the reaction mass and from the crude product operations.

during all processing Example 9- This example illustrates the preparation of; tri-n-butyl isocyanurate and the use of potas slum iodide as a catalyst for the reaction.

Approx;

Parts Molar Ratios 1 Potassium cyanate (92.6%) 87.5 1.0

n-Butyl chloride 97. 5 1. 05 Potassium iodide 5. 0 Acetonitrile 391. 4

were mixed and heated together with agitation in a rocking-type autoclave under superatmospheric pressure for 3 hours at C., after which the reaction mass was filtered. After removing the low-boiling material by distillation at atmospheric pressure, the following cuts were obtained by distilling the remainder of the material under reduced pressure:

Temper- P ressurc mute Cut 1 Partly solid.-

Cut Bwas dissolved in hexane and then cooled in an ice bath. The compound N,N'-di-l'lj butylurea, which separated from the cooled solu- 2 tion, was filtered off and dried. The yield of. The filtratewas distilled, yielding 30 parts of crude tri-nbutylisocyanurate, boiling at l32-150 C. under Further purification by redistillation, using a higher fractionating column, gave 25.5 parts (27% of the theoretical) of trin-butyl isocyanurate, B. P. 151-155 C. at 0.9.- mm., and showing the following upon analysis for.

N,N'-di-n-butylurea was 16 parts.

0.05 mm. pressure.

nitrogen:

aniline to give a solid, M. P. 121 C., which was found by analysis to be N-n-butyl-N-phenylurea.

Per cent N- Calculated for N-n-butyl-N-phenylurea 14.59 1 4.48 5

The liquid material collected in the Dry Ice trap;

Found -4 was, therefore, n-butyl isocyanate. Y

Example 10 '1 v This example illustrates the preparation of triallyl isocyanurate using triethyl amine as a catalyst for the reaction.

Molar 7 Parts Ratios Potassium cyanate (92.6%)-.- Allyl chloride.

Acetonitrile.--

mixture of the abov i gredients was heated under reflux with stirrin ;v for go 11911135 in a I? Per cent N Calculated for tri-n-butyl isocyanuratenu' 14.14 Found -1 14.46;

After the first distillation a small amount (approximately 3 parts) of liquid lachrymatory material was collected in a Dry Ice (solid carbon dioxide) trap. This liquid material reacted'with'" Approx.

action vessel placed on" a steam bath, the reflux temperature being 71 C. The reaction mass was filtered and the filtrate was distilled. There was obtained 9 parts of a .fraction which distilled at 112-l29 C. at 0.05 mm. pressure and which, on cooling, partially solidified. This product was identified as a mixture of triallyl isocyanurate and sym.-diallylurea.

The described reaction was carried out initially in an attempt to obtain allyl isocyanate. our other investigations in this field it was believed that if the reaction could be carried out at a temperature much lower than 150 C., using a. suitable catalyst to accelerate the reaction between the alkali-metal cyanate, specifically Example 11 Approx. Parts Molar Ratios Potassium cyanate (92.6%)- I 212'3 1.0 Ally] chloride 240 1. o Acctonitrile 1,174

were heated together in an autoclave under 1 superatmospheric pressure for 3 hours at 150 C.

while stirring the mass with a stirrer revolving at' il'l R. P. M. The reaction mass was filtered to remove solid matter of which 238 parts was obtained. From a nitrogen analysis of the separated solid it was calculated that it contained about 16% of unreacted potassium cyanate.

The low-boiling portion was distilled from the filtrate. One hundred parts was collected. that boiled between 42 C. and 8 1.5" 6., which fractioii, upon analysis, was found to contain 1.8% ofchlorine'. From this analysis it was calculated that about 1.6% of allyl chloride was recovered.- Theremainder of the acetonitrile was removed by' distillation at slightly reduced pressure;

When all of the low-boiling material had been removed, about 308 parts of benzene was added to the residue. The benzene solution was washed with 100 parts of water containing about 6 parts of concentrated hydrochloric acid. After wash mg with water and drying over calcium sulfate, the benzene was distilled ofi. Distillation of the residue under reduced pressure yielded the following:

The 140 parts of crude triallyl isocyanurate constituting fraction I represents a yield of 56% of the theoretical, and more triallyl isocyanurate was obtained from fraction II.

In another run carried out l-nessentially the same manner 915 has first bel-lfl described, the fifsl} From mospheric pressures.

8 cut obtained upon distillation of the benzene-, free residue amounted to 151 parts of crude triallyl isocyanurate, which corresponds to 60.5% of the given in the foregoing examples by way of illustration. Thus, instead of potassium cyanate, any;

of the other alkali-metal cyanates can be used; and instead of allyl chloride or n-butyl chloride, any other active hydrocarbon halide, more particularly an active alkyl, aralkyl, alkenyl or aralkeiiyl chloride, bromide or iodide, numerous era-1 amples of which have been given hereinbefore,

can be used. We prefer to use acetonitril as the reaction medium, more particularly the agent for" improving the solubility of the alkali-metal cyahate in the reaction mass, since the most satisfactory results have been obtained by its use. It will be understood, of course, that other solubiliz'in'g agents (reaction media) can be employed, such as those mentioned hereinb'efore byway of illustration. Likewise, catalysts other than pa; tassium iodide or triethyl amine can be used. The

reaction can be carried out over a fairly wide temperature range, for instance at temperatures within the range of about C.- to about 200 C., preferably within the range of about C. to about 175 C., and at atmospheric or superat- Catalysts which accelerate the reaction are preferably employed when reaction temperatures much below about C. are

used.

We claim:

ester which comprises effecting reaction under heat between (1) an alkali-metal cyanate and (2) a hydrocarbon halide represented by the formula RX, where X represents halogen and R represents a radical selected from the class consisting of alkyl, alkenyl, aralkyl and arall enyl radicals, said reaction being effected while the reactants of (1) and (2) are admixed with an inert, non-hydroxylated solubilizing agent for improving the solubility of the alkali-metal cyanate in the reaction mass, said solubilizing agent,

being selected from the class consisting of acetonitrile, propionitrile, fi-methoxypropioni-trile,- di-' methylcyanamide, acetone, dioXane and nitro 2. A method as in claim 1 wherein the 2111mm;

metal cyanate is potassium cyanate.

3. The method of preparing a trialkyl ism cyanurate which comprises effecting reaction an:

der heat between an alkali-metal cyanate and, an alkyl chloride said reaction being effected while the aforementioned reactants are admixed -w'ith acetonitrile, and isolating the trialkylis'ocyanurate thereby produced from the resulting reaction mass.

4. A method as in claim 3 wherein the alkali metal cyanate is potassium cyanate.

5. The method of preparing an isocyanuric tri nate and (2) a hydrocarbon halide represented 1. The method of preparing an isocyanuric triby the formula RX, Where X represents halogen and R represents a radical selected from the class consisting of alkyl, alkenyl, aralkyl and aralkenyl radicals, said reaction being efiected while the reactants of (1) and (2) are admixed with an inert, non-hydroxyla'ted solubilizing agent for improving the solubility of the alkali-metal cyanate in the reaction mass, said solubilizing agent being selected from the class consisting of acetonitrile, propionitrile, fl-methoxypropionitrile, dimethyl cyanamide, acetone, dioxane and nitrobenzene, and isolating the isocyanuric triester thereby produced from the resulting reaction mass.

6. A method as in claim 1 wherein th inert solubilizing agent is acetonitrile.

7. The method of preparing triallyl isocyanurate which comprises effecting reaction under superatmospheric pressure, at a temperature within the range of about 100 C. to about 175 0., between (1) potassium cyanate and (2) allyl chloride while the reactants of (1) and (2) are admixed with acetonitrile in an amount sufficient to improve the solubility of the potassium cyanate in the reaction mass, and isolating the triallyl isocyanurate thereby produced from the resulting reaction mass.

8. The method of preparing a trialkenyl isocyanurate which comprises effecting reaction under heat between an alkali-metal cyanate and an alkenyl chloride, said reaction being effected while the aforementioned reactants are admixed with acetonitrile, and isolating th trialkenyl isocyanurate thereby produced from the resulting reaction mass.

9. The method of preparing triallyl isocyanurate which comprises effecting reaction under heat between an alkali-metal cyanate and allyl chloride, said reaction being effected while the aforementioned reactants are admixed with acetonitrile in an amount suilicient to improve the solubility of the alkali-metal cyanate in the reaction mass, and isolating the triallyl isocyanurate thereby produced from the resulting reaction mass.

10. A method as in claim 9 wherein the alkalimetal cyanate is potassium cyanate.

11. The method of preparing a, triaralkyl isocyanurate which comprises effecting reaction under heat between an alkali-metal cyanate and an aralkyl chloride, said reaction being effected while the aforementioned reactants are admixed with acetonitrile, and isolating the triaralkyl isocyanurate thereby produced from the resulting reaction mass.

12. The method of preparing a triaralkenyl isocyanurate which comprises effecting reaction under heat between an alkali-metal cyanate and an aralkenyl chloride, said reaction being effected while the aforementioned reactants are admixed with acetonitrile, and isolating the triaralkenyl isocyanurate thereby produced from the resulting reaction mass.

DONALD W. KAISER. DAGFRID HOLM-HANSEN CHURCH.

REFERENCES CITED The following references are of record in the file of this patent:

Berichte de deut Chem. Ges, 5, pp. 91 and 93 

1. THE METHOD OF PREPARING AN ISOCYANURIC TRIESTER WHICH COMPRISES EFFECTING REACTION UNDER HEAT BETWEEN (1) AN ALKALI-METAL CYANATE AND (2) A HYDROCARBON HALIDE RESPRESENTED BY THE FORMULA RX, WHERE X REPRESENTS HALOGEN AND R REPRESENTS A RADICAL SELECTED FROM THE CLASS CONSISTING OF ALKYL, ALKENYL, ARALKYL AND ARALKENYL RADICALS, SAID REACTION BEING EFFECTED WHILE THE REACTANTS OF (1) AND (2) ARE ADMIXED WITH AN INERT, NON-HYDROXYLATED SOLUBILIZING AGENT FOR IMPROVING THE SOLUBILITY OF THE ALKALI-METAL CYANATE IN THE REACTION MASS, SAID SOLUBILIZING AGENT BEING SELECTED FROM THE CLASS CONSISTING OF ACETONITRILE, PROPIONITRILE, B-METHOXYPROPIONITRILE, DIMETHYLCYANAMIDE, ACETONE, DIOXANE AND NITROBENZENE, AND ISOLATING THE ISOCYANURIC TRIESTER THEREBY PRODUCED FROM THE RESULTING REACTION MASS. 